# Equations of a plane

- Author:
- Sebastian Williams

- Topic:
- Equations

The three points A, B and C define a plane in space.
The vectors AB and AC are two vectors that span the plane from the position vector of point A.
The vector AD is the

**normal**(perpendicular) to vectors AB and AC. Using the normal vector is another way to define a plane (see**g**). That is the**Cartesian equation**of a plane.This page is a good starting point to investigate planes in 3D.
You may start by adjusting the points to match any problem you are investigating.